A. Field of Endeavor
This invention applies to the field of dentistry and, more specifically, to endodontics within that field.
B. Description of Prior Art
At the current time (Feb.-15-2002), endodontic files and reamers with metal shafts and plastic handles are commonly used to clean and measure the length of root canals in teeth with the aid of electronic apex locating devices. This is accomplished by placing a file in the root canal and then attaching or touching a special probe or file holder from an electronic apex locator to the metal shaft of the file to complete an electronic circuit.
The problem commonly encountered by this system is one of access to the metal shaft in the posterior teeth where short files are needed most often but, frequently, end up with the shaft totally within the crown of the tooth being treated. When endodontics is performed on teeth with metal crowns, the metal shaft of the file or the metal probe will short circuit the apex locator if either touch the metal restoration. Insulating sheaths are available to cover the file shaft but they also limit access for the probe. On occasion, a cut is made through the plastic handle to reach the extension of the metal shaft in the handle in order to get an accessible contact point for the probe.
The above problems result in extended treatment time which translates into additional cost for this procedure.
Prior Art Pike et al (U.S. Pat. No. 3,753,434), Mousseau (U.S. Pat. No. 3,916,529), Arai (U.S. Pat. No. 4,243,388), Dery (4,353,693), Shirota (U.S. Pat. No. 5,112,224), Stevens (U.S. Pat. No. 5,421,727), Matsutani et al (5,775,902) and Weber (U.S. Pat. No. 6,520,773) are made of record.